Control of CREB-binding protein signaling by nuclear fibroblast growth factor receptor-1 - A novel mechanism of gene regulation

In integrative nuclear fibroblast growth factor receptor-1 ( FGFR1) signaling a newly synthesized FGFR1 translocates to the nucleus to stimulate cell differentiation and associated gene activities. The present study shows that FGFR1 accumulates and interacts with the transcriptional co-activator CREB-binding protein ( CBP) in nuclear speckle domains in the developing brain and in neural progenitor-like cells in vitro, which accompanies differentiation and postmitotic growth. Cell differentiation and gene activation by nuclear FGFR1 do not require tyrosine kinase activity. Instead, FGFR1 stimulates transcription in cooperation with CBP by increasing recruitment of RNA polymerase II and histone acetylation at the active gene promoter. FGFR1 is a multifactorial protein whose N terminus interacts with CBP and C terminus with ribosomal S6 kinase 1 ( RSK1). Nuclear FGFR1 augments CBP-mediated transcription by 1) releasing the CBP C-terminal domain from RSK1 inhibition and 2) activating the CBP N-terminal domain. The interaction of FGFR1 with CBP and RSK1 allows activation of gene transcription and may play a role in cell differentiation.